I'm voting for the 2017 Summer Specials. I think if any Gen4 is going to end up being collectible it has to be a relatively short run AND not recognized as possibly collectible down the road - meaning those who own them don't treat them like collectibles and lose the boxes, carry them in holsters, etc. Obviously anything that's just extremely short run would be the exception. I think a possible candidate might be the 2017 Summer Specials, the Gen4 17 and 19 with front serrations. When I do see them on Gunbroker they're almost never advertised as Summer Special and I suspect the buyers are buying to use/carry (at least I hope so). My only concern is that NIB do continue to show up so I have no idea what the actual production might be.